1. Field of the Invention
The present invention relates to a plumb-bob device used on construction cites for a level pointing operation, i.e., indicating the positional relation between a floor surface and a ceiling surface.
2. Description of the Prior Art
A well-known plumb-bob device of the pertaining type indicates a leveling reference point by emitting a light beam, such as a laser beam. This plumb-bob device comprises a beam-emitting housing, which emits a linear light beam indicating a floor reference point from its lower end and also emits a linear light beam indicating a ceiling reference point from its upper end toward a ceiling surface, and a plurality of legs mounted by a gyroscope mechanism on and around the beam-emitting housing. The beam-emitting housing accommodates as light sources a high light intensity LED and a visible semiconductor laser, for instance. In the level pointing operation, a linear light beam is cast from the lower end of the beam-emitting housing closet onto a floor surface, thus indicating a floor reference point. Also, a liner laser beam is cast from the upper end of the beam-emitting housing onto a ceiling surface, thus indicating a ceiling reference point.
In the above prior art plumb-bob device, however, the legs are made from pipes or bars, and greatly project from the beam-emitting housing when they are held in an expanded state. Besides, the beam-emitting housing has a considerably large size. Therefore, even a plumb-bob device of reduced size is insufficient for being freely carried on the construction site.
Furthermore, the construction site is usually occupied by various machines and apparatuses, and therefore it may be difficult to secure sufficient space for storing the plumb-bob device. Accordingly, a plumb-bob device which is smaller in size and can be quickly and conveniently handled in use has been demanded.